Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays

Barnes, Michael; Dudbridge, Michael; Duckett, Tom

doi:10.1016/j.jfoodeng.2012.02.040

Cited by 13 publications

(10 citation statements)

References 17 publications

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“…The use of an RGB camera is limited to the inspection of transparent films, and the detection of liquid contaminants is difficult even in these transparent films due to spreading of the liquid within the seal area. Barnes et al (2012) used polarized light stress analysis and laser scatter imaging for seal inspection in polymer trays, yet up to now, the application was limited to transparent packaging materials [14]. Song et al (2014) presented a methodology called "high voltage leak detection", which can only be used for the inspection of non-conductive packaging concepts containing liquid-based food products in contact with the packaging material [15].…”

Section: Related Workmentioning

confidence: 99%

Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging

D'huys¹,

Saeys²,

Ketelaere³

2016

J. Imaging

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Packaging protects food products from environmental influences, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the quality of the packaging material and of the closure or seal. A common problem possibly jeopardizing seal quality is the presence of seal contamination, which can cause a decreased seal strength, an increased packaging failure risk and leak formation. Therefore, early detection and removal of seal contaminated packages from the production chain is crucial. In this work, a pulsed-type active thermography method using the heated seal bars as an excitation source was studied for detecting seal contamination. Thermal image sequences of contaminated seals were recorded shortly after sealing. The detection performances of six thermal image processing methods, based on a single frame, a fit of the cooling profiles, thermal signal reconstruction, pulsed phase thermography, principal component thermography and a matched filter, were compared. High resolution digital images served as a reference to quantify seal contamination, and processed thermal images were mapped to these references. The lowest detection limit (equivalent diameter 0.60 mm) was obtained for the method based on a fit of the cooling profiles. Moreover, the detection performance of this method did not depend strongly on the time after sealing at which recording of the thermal images was started, making it a robust and generally applicable method.

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Section: Related Workmentioning

confidence: 99%

Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging

D'huys¹,

Saeys²,

Ketelaere³

2016

J. Imaging

View full text Add to dashboard Cite

show abstract

“…Shuangyang (2010) studied the inspection of seal quality using machine vision 10 . Barnes et al (2012) used polarized light stress analysis and laser scatter imaging for seal quality inspection in polymer trays and Song et al (2014) presented a methodology called 'high voltage leak detection' 11,12 .…”

mentioning

confidence: 99%

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

2015

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In the food industry packaging is often applied to protect the product from the environment, assuring quality and safety throughout shelf life if properly performed. Packaging quality depends on the material used and the closure (seal). The material is selected based on the specific needs of the food product to be wrapped. However, proper closure of the package is often harder to achieve. One problem possibly jeopardizing seal quality is the presence of food particles between the seal. Seal contamination can cause a decreased seal strength and thus an increased packaging failure risk. It can also trigger the formation of microchannels through which air and microorganisms can enter and spoil the enclosed food. Therefore, early detection and removal of seal-contaminated packages from the production chain is essential. In this work, a pulsed-type active thermography method using the heat of the sealing bars as an excitation source was studied for detecting seal contamination. The cooling profile of contaminated seals was recorded. The detection performance of four processing methods (based on a single frame, a fit of the cooling profile, pulsed phase thermography and a matched filter) was compared. High resolution digital images served as a reference to quantify contamination. The lowest detection limit (equivalent diameter of 0.63 mm) and the lowest processing time (0.42 s per sample) were obtained for the method based on a single frame. Presumably, practical limitations in the recording stage prevented the added value of active thermography to be fully reflected in this application.

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“…In a study completed by Barnes et. al [2], polarized light and laser scatter technology had an accuracy of 96% and 90%. Overall, polarized light and laser scatter technology identify defects in the seal but cannot determine if the defect has an effect on the hermetic seal.…”

Section: Quality Controlmentioning

confidence: 99%

“…It is a non-destructive process that uses linear polarized light to pass through transparent film, which shows a color stress pattern once the light passes through the second light filter. Laser scattering imaging is another non-destructive process that measures the light that is deflected from the contaminant found in the seal area [2].…”

Section: Quality Controlmentioning

confidence: 99%

Effect of Liquid Contamination on Hermeticity and Seal Strength of Flexible Pouches With Lldpe Sealant

Cese¹,

Saha²,

Roy³

et al.

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Flexible packaging is a growing successful market and the majority of flexible package applications are for the food industry. The demand for process optimization and reduced production costs, has led to an increase in flexible packaging. However, fast production lines can result in contamination in the seal area. For flexible food packaging, contamination is considered any food particle or substance trapped in the seal area. Current quality control processes can detect contamination in the seal area, but it is not determined if seal contamination effects seal quality. Oil-based and sodium based snack foods are two common categories that can be packaged on a horizontal flow film and seal (HFFS) flow-wrap machine. The study uses vegetable oil and a salt water solution to simulate the effect of liquid contamination along the Tpoint of flexible pouches made on an HFFS. The T-point refers to where the fin seal meets the end seal and requires the seal jaw to seal through four layers of film, which is the most difficult point to seal. The study tests a combination of different sealing temperatures and dwell time to determine the optimal sealing condition for a hermetic seal. A quality hermetic seal provides an enclosed seal with no leaks due to successful polymer chain entanglement between the two sealant layers. The different test categories of the study are non-contaminated (control), salt water solution for salt based foods, and vegetable oil for oil-based foods. Given the test parameters of the study, 140⁰C sealing temperature and 0.3 seconds dwell time are considered to be the optimal sealing condition for all three test categories. For Phase 1 of the study, salt water has a lower hermeticity pass rate compared to vegetable oil and non-contaminated seals. In addition, the effect of refrigerated storage temperature and ambient storage temperature did not show to be significant for any of the test categories. However, refrigerated conditions showed a higher hermeticity pass rate, but it was not statistically different. The findings for seal strength indicated no test category had higher or lower seal strength over the 14 day test period. Overall, the study shows there is no effect of liquid contaminant on hermeticity and seal strength for flexible film with LLDPE sealant layer.v ACKNOWLEDGMENTS

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Polarised light stress analysis and laser scatter imaging for non-contact inspection of heat seals in food trays

Cited by 13 publications

References 17 publications

Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging

Active Infrared Thermography for Seal Contamination Detection in Heat-Sealed Food Packaging

Detection of seal contamination in heat sealed food packaging based on active infrared thermography

Effect of Liquid Contamination on Hermeticity and Seal Strength of Flexible Pouches With Lldpe Sealant

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